What the Fallacy?!
Tu Quoque
The Fallacy
Avoiding having to engage with criticism by turning it back on the accuser - answering criticism with criticism.
Why it's wrong
Literally translating as 'you too' this fallacy is also known as the appeal to hypocrisy. It is commonly employed as an effective red herring because it takes the heat off someone having to defend their argument, and instead shifts the focus back on to the person making the criticism.
Example
When the doctor advised his patient to quit smoking for better lung health, the patient laughed and pointed out that the doctor himself had a pack of cigarettes in his pocket.